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  • Writer's pictureStudent Wellbeing Service

Circadian rhythm dictates our sleep but it’s ‘ultradian rhythm’ that determines our daily function

Here's why that's important.......


We’re obsessed with being productive – and that’s led to the cult of routine. But writer Libby Heeley argues that by focusing on early mornings and to-do lists, we’re neglecting our natural rhythm.

We are a nation obsessed with productivity. From 4am alarms to self-professing mantras and ice-cold showers, an optimised morning routine has been sold as the salve to all our plights.  

If we could just be better organised, more consistent, less distracted, we can do and be better. But routines are, by nature, aspirational – a meticulously time-blocked Monday morning so easily dismantled by high-priority emails and last-minute meeting requests.  

That’s where routine’s more compassionate cousin, rhythm, comes in: following a pattern of activity rather than a strict time-based schedule. Similar to how circadian rhythm determines our sleeping habits, the ultradian rhythm determines the way we function throughout the day. And while the circadian rhythm cycles once every 24 hours – where we are alert for part of the day and move towards drowsiness and sleep later on – the ultradian rhythm cycles multiple times a day.

“During a cycle, the brain enters peaks and troughs,” explains Kobi Simmat, director and CEO of global business improvement agency the Best Practice Group. The peaks represent optimal or heightened levels of brain activity, he explains, while during the troughs, we become sluggish and operate on a lower frequency. Think: the post-lunch slump.


In essence, human bodies aren’t built to operate continuously like machines – we quite literally cycle between rest and activity. Simmat suggests that by sticking to unmovable routines, we could be ignoring our body’s natural intelligence and opportunity for maximum efficiency. To increase our productivity and energy levels, we need to find and cultivate a unique rhythm: an established melody that allows for improvisation that won’t leave us exhausted by the end of the day.

When looking at productivity specifically, we are concerned with the type of ultradian rhythm known as the basic rest-activity cycle (BRAC). BRAC was first coined in 1960 by physiologist Nathaniel Kleitman and his research assistant Eugene Aserinsky. It’s a rhythm that plays out in 80 to 120-minute cycles non-stop, day and night.

The benefits of working in 90-minute intervals

Inspired by this research, PhD researcher Ernest Rossi suggested that during waking hours, optimal performance is achieved by working in intervals of 90 minutes of activity followed by 20 minutes of rest. In his book 20-Minute Break, Rossi warns that ignoring the body’s natural need for rest could lead to ‘ultradian stress syndrome’, saying: “You will get tired and lose your mental focus, you tend to make mistakes, get irritable and have accidents.” However, when we learn how to recognise the need to take a break, we convert stress into what Rossi calls the ‘ultradian healing response’. He describes that as the “wonderful feeling of comfort and wellbeing that happens when you allow yourself the freedom to take well-deserved rest”.

Ignoring the body’s natural need for rest could lead to ‘ultradian stress syndrome’, which is when you get tired, lose mental focus and make mistakes.

Of course, it’s all too easy to jump on the ‘always on’ bandwagon. Whether that’s being physically active all day – racing from a morning gym class to work meetings and straight out for dinner with friends – or constantly mentally stimulated, strapped to our desks while relentlessly plugged into a minute-by-minute news cycle. In the office especially, we have the tendency to cast everything out of mind until the job at hand is complete. But concentration, when taken to the extreme, can become a liability. And forcing yourself into an unrealistic working paradigm will only backfire.


So, how can we use ultradian rhythm in the context of our professional and personal lives for increased productivity and energy? Rossi suggests that when you lay out your activities for the day, you should take two things into consideration:

  1. Ensure that the segments of your day on a particular task do not stretch for more than 90 minutes at a time.

  2. Allow yourself and those around you to take a break every 90 minutes, ideally allowing for 20 minutes before transitioning into a new activity cycle.

The period of rest can include anything that feels refreshing: breathwork or meditation, a short walk or yoga session are all great. These moments are about changing your focus and/or environment. If you sit at a screen all day, don’t fill your breaks with scrolling – try to do something active or get outside for some fresh air. That phone-free break every 90 minutes could be the simple solution to our never-ending battle with overwhelm and tiredness.


Your ideal day will be personal to you, but here are a few rhythm-based suggestions to boost productivity and energy flow: AM admin Start the day by replying to your emails and making to-do lists for yourself and/or your colleagues. This will allow you to establish your priorities for the day. Prioritise concentration tasks It’s normal to be met with an early afternoon productivity slump, so try to get tasks that require focus or creativity done early on. Accomplishing something substantial before lunchtime will build a sense of momentum for the rest of the day. Passive PM Post-lunch, we are often at our foggiest and this is the ideal time for more ‘passive’ tasks, like researching for future projects or meeting planning. Allow for wrap-up time Work-from-home culture can make it easier for the workday to roll into the night. Set yourself a hard deadline to down tools. Create a window of time before the end of the day to tie up any loose ends. There will always be times when you have no choice but to burn the midnight oil, but typically, we’re able to control how our days roll out. There’s no right formula for having the ‘best’ day, but the trick is to be honest with yourself about what works for you. If you’re filled with despair at the thought of a morning HIIT workout, schedule it for early afternoon or try an evening pilates class instead. Keep the ultradian rhythm in mind; free yourself from the shackles of strict, unrealistic routine and you’ll be setting yourself up for a more productive, energised future.

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Best wishes, The Wellbeing Team

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